I'm interested in identifying the most common mapping errors you stumble upon from other OSMers (or that you make yourself).

If we could list some of the most common mistakes then we could use that information to drive improvements that may help to prevent the same mistakes being made in the future (e.g. by clarifying the wiki documentation, modifying the editor UI, writing scripts to find the mistakes etc).

This is obviously a very subjective question, but hopefully some people may find the answers useful. Please try to stick to definite actual errors, rather than simple differences of opinion.

This question is marked "community wiki".

asked 06 Oct '10, 15:01

GrahamS's gravatar image

accept rate: 28%

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Not identifying the different segments of a road properly

Often different segments of a given road are given different names. (Typically, the name of the road changes after a major junction or roundabout.)

But often the mapper does not break the road into segments, or provide the correct names to these segments.

This is a common mistake of a mapper who is tracing an uncharted area just using the Bing satellite image, but without much local knowledge.

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answered 13 Mar '15, 07:29

NarayanAras's gravatar image

accept rate: 0%

To draw a building shape, the mapper traces its terrace, but does not move it to its base

This "parallax error" is an extremely common mistake in drawing shapes for highrises.

The mapper uses the Bing satellite image, and traces out the top of the building.

But he forgets that the satellite image is not exactly "top-down", about 15 degrees angle to the vertical. Thus the base of the building does not lie exactly under its top. In fact, the taller the building, the more this offset!

On the other hand, all map features having low heights are traced without such parallax errors. For example, roads, boundary walls, low-rise buildings.

As a result, many tall buildings appear to be shifted from their actual positions. Some even touch (or "crash into"!) the adjoining areas.

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answered 13 Mar '15, 07:20

NarayanAras's gravatar image

accept rate: 0%

Confusion between "Common Name" and "Operator" of a POI

For example, take a Citibank ATM.

  1. Is "Citibank" a 'common name' or 'operator'?
  2. Should "ATM" be a part of the Common name?

Another example: A Dominos pizza joint. Legally, "Dominos" is the brand, operated by a local franchisee (a separate business entity). So how to fill these attributes?

As a result, I have seen inconsistent entries in POIs.

Suggested solution: The mapping tools (iD/Potlatch) should have more explicit tooltips.

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answered 13 Mar '15, 07:03

NarayanAras's gravatar image

accept rate: 0%

Forgetting to add any tags to newly created nodes and ways !

I think this is a result of a combination of users mistakingly believing that they had deleted the untagged way or node, they didn't know at all that they created the node or way, a

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answered 10 Jan '13, 15:42

skorasaurus's gravatar image

accept rate: 12%

iD unfortunately makes it way too easy to do this. Potlatch 2 also lets you commit an untagged way without any sort of warning (in fact when I was still switching from iD to Potlatch 2 just to add parallel ways, and then switching back to do the rest of a dualize, I took advantage of this). JOSM will at least warn you, but how many newbie editors use JOSM?

(15 Dec '14, 07:02) skquinn

Some of the varied mistakes I've seen that I remember:

  • Stuffing ad copy in places where it isn't appropriate: note=* tag, changeset comments, or notes. I have nothing against marketing/PR/SEO people (in fact I've been one for a while) but there's a time and a place for everything.
  • Taking over a road segment or other object to add a business listing. As bad as ad copy may be, this is much worse and much harder to clean up.
  • Vandalism of the road layout, such as dragging a bunch of points together that clearly don't belong.
  • Putting any old garbage in opening_hours=*.
  • Putting incorrectly formatted phone numbers (not international format) in phone=*.
  • Abbreviating street names, whether mapping the actual road or in an address.
  • Various other address bloopers, like trying to stuff the whole street address in addr:housenumber=*.

Of course, I'm sure I'll see some completely new, weird, and not-so-wonderful mistake right after adding this.

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answered 15 Dec '14, 07:00

skquinn's gravatar image

accept rate: 0%

In Africa highway mapping, track only goes to farmland.

So ruled in Highway_Tag_Africa.

"The road conditions in African countries do not always correspond to their economic and social role. A road typology should be based on the road importance and not on the surface or the visual appearance of a road."

This means, it may look like a track but, if it goes from a major road to a hamlet, it's an unclassified highway, except a 4x4 can't drive it because it wiggles too much (then it's a path). Ditto from hamlet to hamlet.

People new to Africa mapping always get this wrong.

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answered 13 Dec '14, 14:51

rwst's gravatar image

accept rate: 0%

That's not so different from other countries. The highway tag should be used to tag the road classification, not the road's look.

(13 Dec '14, 17:13) scai ♦

Not Mapping!

The most common mistake users make, is to register for OpenStreetMap, but then fail to do any map editing at all. Strange but true! See pascal's „Nominal Members“ of OSM? blog post.

Please all you people. Have a go at mapping! Make mistakes. We don't mind.

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answered 06 Oct '10, 17:03

Harry%20Wood's gravatar image

Harry Wood
accept rate: 14%

edited 07 Oct '10, 09:47

GrahamS's gravatar image



Absolutely Harry. I'm keeping a careful eye on this post because I definitely don't want it to turn into a set of "slag off the noobs" answers. I'm interested in finding where the common problems are so we can help the noobs (and everyone else).

(06 Oct '10, 17:21) GrahamS

As a new user who's registered but not (yet) edited the map, I'll suggest that some sort of introduction to editing the map is desperately needed. Or if there is one, it needs to be much more prominent; I found my way to this "help centre" looking for such a guide, and still haven't found one. I'll be glad to have a go at mapping once I figure out how!

(13 May '11, 19:17) cmadler

Update: Via the blog post linked above, I found my way finally to the Beginners' guide, but I'll suggest that it should be much easier to find!

(13 May '11, 19:27) cmadler

I'm not surprised that MANY people sign up then give up. The instructions and answers are spread over many different systems and I haven't found answers to some pretty basic questions yet. I had to create a second login to post this comment and more logins are required to participate in discussion groups. I tried watching a video, but it's just too large for my rural connection. I am very discouraged at this point. I edited databases from '75 to '88 and continued with systems design work until '01 but I'm not sure that I can find out how to help here.

(22 Oct '12, 00:55) etch-a-map

Absolutely agreed re "The instructions and answers are spread over many different systems". While things are getting better (this help site didn't exist when I started, for example) there's still a long way to go.

One of the places that I'd suggest asking "what's it all about then" questions is the "newbies" list. It's relatively low traffic, so if you subscribe you won't get swamped.

Another is the "#OSM" IRC channel. There's a wide range of different discussions in there at any one time but if you ask a question like "how do I do X?" or "I've just mapped Y, does it look OK?" someone will usually be around to reply (if you don't have an IRC client installed you can just use the web client).

There are also various diferent discussion groups within the forum, and for a general "contact" overview see this page.

(22 Oct '12, 09:07) SomeoneElse ♦

Go mapping!

Yes, but don't map ignoring the licence and contributor terms. Mapping from Google is wrong but there are lots of allowed sources (including the Bing imagery covering the world by satellite in medium resolution, plus US and most of Europe in high resolution Aerial orthophotography). But let's not forget that Bing imagery is frequently old (often more than 5 years, and even the last monthly updates in Bing are photos dating almost one year). But DON'T REMOVE data you don't understand or that you don't like rendered because it's "ugly" for your eyes or invisible in Bing images!

(27 Nov '12, 10:14) Verdy_p

Another reason for people not feeling brave enough to start is that the default editor which comes up when I click 'Edit' is Potlatch 2, but the online tutorial I was sent a link to when I signed up shows a different or older editor, bearing little visual resemblance to Potlatch 2. Also, no warning was given that the Bing imagery is not necessarily exactly aligned. I merrily set to work adjusting local buildings and roads by 2 or 3 metres wondering why so many were a bit out.

(02 May '13, 16:13) Jonga

What's the URL of the online tutorial that you were sent so that we can get it changed?

(02 May '13, 16:17) SomeoneElse ♦

I'm a newbie. I'll say that although there is definitely available documentation it is very confusing to have docs for iD, P2, JSOM all mixed together. Also, I didn't find any that are comprehensive from a beginners perspective, they include how to add a POI but tagging that POI is covered in a very high level gloss. For example, I am trying to figure out (please don't feel the need to answer here, I've already asked in the forum...) how to add a golf=driving_range tag but can't to find specifics. iD only offers me some of the tag options and I'm not sure where to put it in P2 or JOSM.

(30 Aug '13, 20:32) jaseiny

Hello, I registered today since I am using OSM heavily on my ANDROID phone during my trip in Japan and intend to contribute. Looking for a tutorial, I came here. Here a good tutorial on creating OSM maps: https://help.openstreetmap.org/questions/28251/interactive-tutorial-to-getting-started-editing-osm including the following links: http://learnosm.org/en/ http://wiki.openstreetmap.org/wiki/Beginners%27_guide This should save you at least 30 minutes of searching around for tutorials, beginners guides, OSM basics, etc.....

(23 Aug '14, 04:22) ostino
showing 5 of 10 show 5 more comments

Sometimes users forget to mark that location which is most important for the people during travel like signs of hospitals, fire brigade and shopping complex. Hope you can understand the fact behind mapping.

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answered 08 Jul '14, 06:37

denygarcia's gravatar image

accept rate: 0%

edited 08 Jul '14, 10:42

SomeoneElse's gravatar image

SomeoneElse ♦

I would not classify this as mistake, people are not obliged to map. Contributing something that you consider not the most important thing is NOT a mistake.

(16 Jul '14, 23:41) Mateusz Koni...

Deleting nodes whose tag's don't show up in Potlatch 2. I have seen situation where new users will "clean up" nodes whose tags are "Not recognised".

Hopefully this will be going away with the greater prominence of iD.

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answered 06 Jul '14, 13:58

InsertUser's gravatar image

accept rate: 23%


Missing Bridges

Quite often in OSM, we find two roads (or road/railway or road/waterway) crossing in OSM without any information about the intersection. Thus we don't know if it is really an intersection (simply put a node) or if it is crossing at different levels (don't put a node but split the way to extract a small segment and tag it with 'bridge=yes' and 'layer=1') (or 'tunnel=yes' if it is a tunnel).
Even if you don't know exactly where the bridge/tunnel is starting/finishing, it's better to have approximate length than leaving a question mark on the map (because it's reported by almost all quality assurance tools and cannot be fixed without a second survey). And please, don't put a node if both ways are at different layers even if you tag them correctly, otherwise some routing application might think that the link exists (e.g. steps) and might create routes through some connections that do not exist in reality.

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answered 08 Oct '10, 15:12

Pieren's gravatar image

accept rate: 15%

edited 08 Oct '10, 15:40


because it's reported by almost all quality assurance tools and cannot be fixed without a second survey

I've more then once found where people who look at the quality assurance tools think they can fix this without a second survey. They draw a bridge where there is no bridge in the real world. This is really irritating, because it replaces a very visible error with an error that is hard to find.

(24 Nov '12, 16:29) cartinus

For truck routing it would be also extremely useful if you could as well specify, if there are any height restrictions underneath bridges!

Please check the OSM Wiki for Maxheight tag. There's also a QA tool around to help you find potential missing maxheight tags in your area (-> search wiki for "Maxheight Map").

(03 Jul '14, 20:41) mmd
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question asked: 06 Oct '10, 15:01

question was seen: 34,548 times

last updated: 13 Mar '15, 07:29

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